OP: Towards high performance nanowire photonic devices: Novel testing techniques and device structures

University Of Iowa, Iowa City IA

Investigators

Abstract

Abstract title: Towards high performance nanowire photonic devices: Novel testing techniques and device structures Abstract Non-technical: This grant will focus on research and development of semiconductor nanowires, materials with diameters just a few tens of nanometers but lengths of microns. Semiconductor nanowires create the possibility of structuring materials in all three dimensions, with a greater range of elements and compounds within the nanowire, and through ordered arrays and patterns of nanowires. The importance of structuring semiconductor materials for photonic devices (devices that work with light) is illustrated historically. For example, semiconductor heterostructures have made possible solid state lighting, high efficiency light emitting diodes that are replacing incandescent and fluorescent lighting (2014 Nobel Prize in Physics). For semiconductor nanowires to become competitive, a number of challenges need to be overcome. One is that the quality of semiconductor nanowires are currently far below that of conventional planar materials (semiconductors arranged in layers). In this grant, we will use a novel optical technique to resolve the nanowire quality in different parts of the wire, e.g. sides, ends, interior. Second, we will seek to develop semiconductor nanowires that emit at mid-infrared wavelengths with novel semiconductor materials combinations, such as layering within the nanowires and further reducing the nanowire diameter. Third, we will seek to modify and control the light emission characteristics of the semiconductor nanowire devices through patterning and positioning of nanowires in arrays. The rationale for the proposed study is that it will establish a strong scientific framework by identifying the key mechanisms needed to develop high performance mid-infrared III-V nanowire photonic devices. Furthermore, the project goals are synergistic with our broader impacts goal of generating more public awareness, excitement, and understanding in how physics, engineering, and computer modeling can be used to develop technologies that we use in our daily lives. Abstract Technical: A multi-faceted program is proposed to investigate mid-infrared emitters and metamaterial optical components from bottom-up, III-V nanowires and nanowire heterostructures. Due to a capacity to accommodate strain through lateral expansion, new material combinations become possible in nanowires. New alloy compositions and substrate materials can be contemplated in indium arsenide (InAs)/indium arsenide antimonide (InAsSb) superlattice nanowires compared to planar materials, a promising mid-infrared material due to remarkably a small non-radiative Shockley-Read-Hall recombination coefficient but unfortunately high non-radiative Auger recombination coefficient. New material combinations and lateral quantum confinement in nanowires give new possibilities to suppress Auger with bandstructure engineering. Radiative recombination of carriers in nanowires will be modified and controlled by variation of nanowire size, pattern, and periodicity. Mid-infrared III-V nanowires will be grown using selective area epitaxy, a technique giving precise control over nanowire pattern and size. A novel optical measurement technique will be used to spatially resolve recombination coefficients (Shockley-Read-Hall, Auger, radiative) inside nanowires. Nanowire emission from light emitting diodes to amplified spontaneous emission to lasing will be measured. Nanowires will also be investigated as passive mid-infrared optical components to improve light extraction and collimation from light emitting diodes. Nanowire filters and 2D photonic crystals will be modeled, grown, and measured.